1. CETACEA

2. The Cetacea are one of the most distinctive and highly specialized orders of mammals. They include the largest animal that is alive, the blue whale; the highly intelligent and communicative dolphins; the tusked narwhals and blind river dolphins and singing humpback whales

3. Whales have streamline bodies with highly compressed neck vertebrae, dorsal fins, and a tail with two finlike flukes arranged horizontally

4. Modern whales have greatly elongated anterior skull bones, and the nostrils are located on the top of the head, forming the blowhole

5. The forelimbs are specialized to form flippers, and the hind limbs and pelvis are extremely small and do not normally extend out of the body wall of the animal.

6. Cetaceans are nearly hairless, and are insulated by a thick layer of blubber. As a group, they are noted for their high intelligence.

7. Differences between Dolphin, Whales and Porpoise
Killer whales are dolphins

8. One difference between whales, dolphins and porpoises is their size
One difference between whales, dolphins and porpoises is their size. Whales are unarguably the largest with the adult Blue whale growing to m (~ ft); the next largest are dolphins which are generally about meters (~6 - 12ft) long and porpoise are the smallest at meters (~4 - 7 ft) depending on the species.

9. Other differences can be found in the teeth, or in some cases the lack of teeth

10. Some whales called the Odontoceti or ‘Toothed Whales’ have teeth which are used to eat fish and squid, dolphins and porpoise are part of this group and so are classed as species of the greater whale family

11. Other whales called Baleen Whales use baleen which is an elastic, horn-like material that hangs in fringed plates from their upper jaws

12. Baleen is used to filter krill and zooplankton from the water

13. Dolphins and porpoises are separated taxonomically by their teeth; dolphins have conical teeth and porpoise have spade-shaped teeth. The different teeth being designed to catch different sized fish.